Temperature fusible plug for spraying apparatus



NOV. 6, 195] w Q ELDT TEMPERATURE F-USIBLE PLUG FOR SPRAYING APPARATUS Filed July 15, 1948 Patented Nov. 6, 1951 TEMPERATURE FUSIBLZE PLUG FOR I SPRAYING APPARATUS 7 1 rank W. am, Carnot, Pal, assignor to Homestead Valve Manufacturing Company, Cora- "opolis, Pa., a corporationot Pennsylvania,

Application July 15, 1948, Serial No. 38,833

This invention relates generally to temperature protective devices and more particularly to method and apparatus for thermally protecting the hose or heat sensitive device of spray generatorsand including fuse plugs foruse with spray generating apparatus.

- Spray generating apparatus is designed to supply metered quantities of liquid which is heated to produce a spraymixture of the liquid and the vapor of a liquid that is discharged througha hose and a nozzle in the form of a spray. By properly proportioning the liquid and the steam,

or the liquid and fuel used to produce the spray.

mixture, a spraying apparatus may be made to operate within the latent heat range which provides flash vaporization at the nozzle resulting in a spray having a temperature of two hundred and twelve degrees F. at the nozzle opening." By properly designing the nozzle different types of sprays may be produced for various purposes such as a finely atomized spray for close cleaning and agricultural sprayi g of bushes, trees and ground crops or the spray may have a solid center for use in cleaning a surface several feet away.

Regardless of the character or type of generating apparatus, the nozzle employed, or the controls provided for maintaining proper operation of the spray generator, operators frequently allow the liquid supply to run low which causes air to be pumped with the remaining liquid. The proper metered quantity of liquid will of course not be supplied to the heating zone of the generator and the smaller quantity of liquid is converted into excess or superheated steam. Under such conditions the fuel supplied is metered for a materially greater quantity of liquid and thus overheats the liquid producing the steam. A flexible rubber hose is used to conduct the spray mixture to a gun whereit is discharged and this hose cannot stand the high temperature of steam or superheated. steam and will therefore be burned out.

The principal object of this invention is the provision of thermal protective method and apparatus wherein a temperature protective device will create a bypass for fluids of predetermined temperature to protect a hose or other heat sensitive device from destruction.

Another object is the provision of a thermal protective device which will create a fluid bypass for the discharge hose or for a heat sensitive device and provide a cooling of the hose or heat sensitive device.

Another object is the provision of a temperature fuse plug enabled to withstand operating temperatures of the spray generator and creat- ZClaims. (c1. rag-504.1

F ing a bypass for fluids at a predetermined perature.

Another object is the provision of selected met als which, when alloyed, provide a thermal fuse plug-having a predetermined softening or melting temperature characteristic for a spray generator apparatus. 7

:;Another. object is the provision of a thermal fuse plug nozzle for use with a hose or heat sensitive device and which is arranged to inspirate cooling fluid through the hose or heat sensitive device when it functions due to excessive heat.

Other objects and advantages appear in the following description and claims.

I The accompanying drawings show for the pur-- pose of exemplification, without limiting the invention or claims thereto, certain practical embodiments of the invention wherein:

Fig. 1 is a diagrammatic view of a spray generating apparatus employing this invention; and- Fig. 2 is a view in section of the bypass and fuse plug comprising this invention.

. Referring to Fig. 1 of the drawings, I represents a liquid supply tank, the level of liquid being controlled by the float 2 arranged to actuate the valve 3 which regulates the flow of liquid from the supply pipe 4. The liquid is withdrawn from the tank I through the pipe 5 by the reciprocating pump 6, the piston l of which is actuated by the crank 8 on the pulley 9 that is rotated by the motor Ill through the belt II.

The positive displacement pump 6 is provided with the inlet and outlet check valves l2 and I3, the latter passing the liquid supplied through the pipe I4 to the heating coil l5. The heated liquid or spray mixture of liquid and vapor of a liquid passes from the coil l5 through the pipe 16 to the temperature protective device I! from whence it flows laterally through the hose l8 and the nozzle 20 of the gun 2|. Heat is supplied to the coil l5 by any suitable means such as the burner 22. The construction and operation of spray generating apparatus of this character may be found in United States Letters Patents 2,289,674, July 14, 1942, Spray Generating Apparatus, and 2,128,263, August 30, 1938, Process and Apparatus for Heat Generation of Spray, wherein the liquid is supplied to the heat exchanger in metered quantities and the supply of fuel is correlated therewith to produce a mixture of liquid and vapor of a liquid.

The temperature protective device [1 is shown in Fig. 2 which comprises the T member 24 having the opposed aligned threadedopenings 25 and 26 and the laterally connected smaller bore 21 which opens into the larger threaded bore temthan the bore of *the opposed or fuse plug 34'. The threaded opening 23 is closed by the'fus e plug 34 which consists of a short threaded nipple 35 having a non-round head 36--for tightening;

the same in the thread 26. The bore 3 'F of-T117111 nipple 35 is larger than the bore 33 and the former increases in diameter from th' head 35 inwardly. This bore 31 is'plug'ged- -by -an-talloy of lead and tin as indicated at"'3il;" The alloy of lead and tin has a substantially *con'sta'nt' i softening point temperature of approximately one hundred and eighty-two degrees (ifregar'd less of the relative percentage of lead and tin in an alloy within the limits of from ten toninety percent by weight of lead to from ninety 'to lt'eni percent by Weight of tin.

The tapered plug 3-3 containing-a solid .solution of lead and tin will not melt "or lead; dur-" ingthe normal operation of the spray generator and it is maintained relatively cool by reason of the fact that it aids-in dissipating heat from the liquid spray mixture. However, if theiproportion of metered liquid falls belowthatrequiredby the correlated amount of fuelsupplied to the heat exchanger of the generator; the

heated mixture will reach'a temperature ofone hundred and eighty-two degre'esC. or greater in a'ver'y short time causing the plug 38 to-soften or melt and blow out of the tapered bore 31. Since the tapered bore 3'! is larger in diameter than the opposite bore 33 of the T fitting,- itfunctions as an ejector causing air to be inspirated back through the nozzle; the hose l8,

thenipple 3D, the small bore-21, which air is discharged through the nipple'34'withthe highly heated mixture. Thus the heated- -mixture bypasses the-hose and cool air' 'is drawn: back through the hose to reduce-it's temperature; The hose will stand .the iternper'atures of thesoluti'om below 1' that which is necessary tomelt the plug 38 of-the'solid 'solution of lead and'tin. It-ha's bee-nufou-nd. preferable to" construct th safety device I! with the bore 33 smaller in diameter than the :tapered'hore 3? and the bore 21 s'm'allerthan the bore 33. These-requirementsprovideproper Jinspira'ting or ejector characteristics for drawing air-back through the hose and preveneers being-burned out due toexcessive tem'-' peratures of the spray mixture;

j other I claim: p

1. A device for protecting a discharge hose of a spray generator by cooling comprising a T-fitting with two opposed openings and one lateral opening, said lateral opening being smaller than the other openings, said lateral opening being connected to a discharge hose anda pipe connectingone' of said opposed openings to the generator to conduct the normal flow of heated -sp'ray solution from the generator through the fitting -andc.the. \discharge hose, a nipple in the 'fasaidopposed openings with a larger inside diameter than the pipe making the generator connection} and a fusible plug stopping sa id nipplebutadapted to melt and flow out at rt-predetermined temperature to directly discharge; the-spray solution and inspirate air back through the hose and said lateral opening.

2}'-A-= thermal safety device for conducting heated fluids consisting of a T-fitting having two alignediopenings' and one lateral opening, the lateral opening .being smaller than the; alignedopenings; a plug closing one of the aligned openings sai'd .plug characterized by hav-. ingpredetermined softening andmeltingv char.- acteristics, and means to connect a source-oft heated fluid to normally flow-into said other aligned opening and discharge-out said lateral; opening, excessively heated fiuid melting said-- plug to discharge-directly through the aligned: openings and inspirate air through-the smaller lateral opening and discharge it wan-ma ma out of saidone aligned opening.

W; OFELDT.

REFERENCES CIT-ED The following references are of record in the file of'this patent:

UNITED STAT-ES PATENTS Ger-many Jan. 17, 1933 

